This invention relates to copy protection, particularly but not exclusively to an apparatus and method for protecting digital data on a data storage medium from unauthorised copying.
Although digital media such as audio CDs and CD-ROMs allow perfect reproduction of digital data stored on them, the problems of controlling unauthorised reproduction have so far been mitigated to some extent by the fact that these media have generally only been available in a read-only format, so that the potential infringer needed specialist recording and CD-pressing equipment to make high quality copies.
However, the introduction into the consumer market of recordable digital storage technology, including CD-R (Write Once) and CD-RW (Rewritable), as well as Digital Versatile Disk (DVD) technology, which aims to make low cost digital recorders widely available, has raised the need for sophisticated copy protection systems, to prevent extensive piracy. It is envisaged that DVD recorders, known as DVD-RAM recorders, will eventually replace the various different forms of currently available storage equipment, including computer hard-disk drives and video cassette recorders.
The principles of DVD technology are well established, with DVD-RAM recorders such as the Hitachi GF-1000 series available on the market. Reference is directed to xe2x80x9cDVD Demystifiedxe2x80x9d, by Jim Taylor, published by McGraw-Hill, 1998, for further information on DVD principles.
Without any form of copy control, films, audio recordings and other digital content distributed on DVD disk or CD-ROM, can be easily recorded by a DVD-RAM, or other digital recorder, onto a digital data storage medium such as a recordable DVD disk, from which they can be further copied numerous times onto other DVD disks, without any degradation in the copy quality.
To prevent unauthorised copying, devices sold to consumers incorporate copy protection mechanisms. For example, copy protection information can be embedded in the data sector of a DVD disk, as illustrated in xe2x80x9cDVD Demystifiedxe2x80x9d, by Jim Taylor at page 128. A possible method of copy control using such embedded information is for the digital content provider to supply the film or other digital content on a read-only medium, for example a DVD-ROM disk, with a xe2x80x9cNever-Copyxe2x80x9d flag embedded in the data. The DVD player/recorder will check for the presence of this flag and, if an attempt is made to copy the disk when the flag is present, the recording circuitry will prevent recording. However, this type of protection can be circumvented by using DVD-ROM/RAM drives as peripherals for computers, so as to enable copying of the data from an original disk onto a recordable disk on a bit-by-bit basis, including the copy protection information.
To prevent such bypassing of the protection scheme, some DVD players are designed to check for the presence of Never-Copy flags on recordable disks as opposed to ROM disks. The presence of such a flag on a recordable disk is taken to indicate that the disk is an unauthorised copy of an original ROM disk, so that playback of the data on the disk will be prevented. On the other hand, if the player detects that a ROM disk is being used, it will play back the data on the disk.
However, this scheme works on the premise that a computer user copying the disk will copy all of the data on a bit-by-bit basis, including the Never-Copy flag. The scheme can still be easily bypassed by the computer user who knows or determines where the copy control information is located on an original ROM disk, and who can therefore change or overwrite this information when making a copy of the original disk onto a recordable disk.
A further problem with the above described protection scheme is that it is inflexible, with no way of providing for a copy generation management system (CGMS), which governs the extent to which copying is permitted. For example, there is no way of providing for the contents of an original data storage medium to be copied to a back-up medium, while preventing the production of a further generation of copies from the back-up medium.
The present invention aims to address the above problems.
According to the present invention, there is provided apparatus for processing data stored on a storage medium which has a medium identifier, the apparatus including processing control means operable to control the processing of the stored data in dependence on the relationship between the medium identifier and verification information for the medium identifier stored on the medium, and in accordance with copy control data stored on the medium.
The processing control means can comprise recording control means for controlling the recording of said data from said medium in response to said copy control data.
The medium identifier may be a first medium identifier and the verification information can comprise a second medium identifier, so that the apparatus can prevent playback or recording if the first and second medium identifiers are different.
In the case of an original disk, the second medium identifier may be a copy of the first medium identifier.
The apparatus may include means for authenticating the verification information. The verification information may, for example, be digitally signed, and the authentication means may comprise means for verifying a digital signature.
According to the present invention, there is also provided data storage medium processing apparatus, said storage medium having a medium identifier, said apparatus comprising a playback module operable to control playback of data stored on said storage medium independence on the relationship between the medium identifier and verification information for the medium identifier stored on the medium, and a recording module operable to control the recording of data from said data storage medium on to a recordable storage medium in response to copy control data stored on said data storage medium.
The present invention further provides a method of processing data stored on a storage medium which has a medium identifier and verification information for the identifier stored on the medium, comprising controlling the processing of the stored data in dependence on the relationship between the medium identifier and the verification information, and controlling the recording of data from said medium in response to copy control data stored on the medium.
The present invention also provides recording apparatus for recording data onto a data storage medium having a medium identifier, comprising means for producing verification information for the medium identifier, said verification information to be stored on the medium, and means for controlling recording onto the medium in response to copy control data stored on a medium from which the data is being recorded.
The present invention additionally provides a method of recording data from a first data storage medium having a first medium identifier onto a second data storage medium having a second medium identifier, said first storage medium having copy control data stored thereon which indicates that said data may be copied at least once, comprising the steps of verifying from verification information stored on the first medium that said first medium is an original medium producing verification information for said second medium identifier and storing said information on said second medium.
According to the present invention, there is further provided a data storage medium comprising a medium identifier, verification information for the identifier stored on the medium and copy control data stored on the medium for use in controlling the copying of data from the medium.
Advantageously, in accordance with the invention, digital data on a data storage medium can be protected from unauthorised copying even if the copy protection information in the data is falsified. In addition, the protection scheme provides for the generation of legitimate copies, such as backup copies.